1. Field
The described technology relates generally to a winder for an electrode assembly of a rechargeable battery winding a positive plate and a negative plate, and a separator of the rechargeable battery and an electrode assembly manufacturing method using the same.
2. Description of the Related Art
A rechargeable battery includes a positive plate and a negative plate, both formed by applying an active material onto a current collector, and a separator interposed therebetween. The electrode assembly of the rechargeable battery is formed by stacking the positive plate, the separator, and the negative plate and then winding the assembly into a jelly roll. A winder is used to manufacture the electrode assembly in the jelly roll form. The winder includes a pair of nip rolls, a rotor that rotates below the nip roll, and three winding cores that rotate while being disposed at first, second, and third positions of an equilateral triangle, respectively and move backward or forward from the rotor. The first position is vertically below the nip roll and the second and third positions form a symmetric structure at both right and left sides of an extension line linking the nip roll and the first position with each other while maintaining an interval of 120° in a rotation direction of the rotor.
While manufacturing the electrode assembly of the rechargeable battery using the winder, the rotor moves three winding cores to the first, second, and third positions in sequence. In this case, a first winding core winds the positive plate and the negative plate and the separator at the first position and then moves from the first position to the second position to complete a finishing process of the wound electrode assembly. While in the second position, a cutting process of the separator is performed and the electrode assembly is then removed by moving backward from the second position to the third position. The first winding core prepares for a new winding by moving forward from the third position to the first position.
After winding, the winding core at the first position moves to the second position and another winding core at the third position moves backward to the first position. Therefore, the separator connecting the nip roll and the winding core at the second position deviates from the winding core at the first position by maintaining an inclined state in a vertical direction. Accordingly, a control roll is provided at the side between the first and second positions to push the separator connecting the nip roll and the winding core at the second position towards each other so as to adjust the separator to be vertical between the nip roll and the winding core of the first position. While the separator is in the vertical state, the winding core at the first position moves forward from the rotor to start new winding by using the separator, and the positive plate and the negative plate.
In the winder for the electrode assembly of the rechargeable battery, after winding is completed at the first position of the rotor, in order to start new winding, the separator should be adjusted to be in the vertical state by using the control roll, This results in the structure of the winder being complicated and the time when an empty winding core is moving is lengthened. Therefore, a winding cycle is lengthened which results in decreased productivity.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.